The present invention relates in general to optical switching devices. More particularly, the present invention relates to a liquid crystal cross-connect for an optical waveguide.
One of the current trends in telecommunications is the use of optical fibers in place of the more conventional transmission media. One advantage of optical fibers is their larger available bandwidth handling ability that provides the capability to convey larger quantities of information for a substantial number of subscribers via a media of considerably smaller size. Further, because lightwaves are shorter than microwaves, for example, a considerable reduction in component size is possible. As a result, a reduction in material, manufacturing, and packaging costs is achieved. Moreover, optical fibers do not emit any electromagnetic or radio frequency radiation of consequence and, hence, have negligible impact on the surrounding environment. As an additional advantage, optical fibers are much less sensitive to extraneous radio frequency emissions from surrounding devices and systems. With the advent of optical fiber networks, flexible switching devices are needed to direct light signals between fibers to all-optical domain fiber networks.
One aspect of the invention is an optical device for directing a light signal, including an optical path for propagating the light signal. A trench is formed in the optical path, the trench including a surface region. An alignment layer is disposed on the surface region, and a liquid crystal material is disposed in the trench, the liquid crystal material having a plurality of molecules that are aligned in a first direction by the alignment layer.
Another aspect of the invention is a method of directing a light signal in an optical device, the optical device having a first optical path and a second optical path, the method including forming a trench in a cross-point, wherein the cross-point is a location where the first optical path intersects the second optical path. The method includes forming an alignment layer on a surface region of the trench. The method also includes disposing a liquid crystal material having a plurality of molecules in the trench, wherein the alignment layer causes the plurality of molecules to align in a first direction, and applying a voltage to the liquid crystal material to thereby change an alignment of the plurality of molecules from the first direction to a second direction to cause a portion of the light signal to be directed from the first optical path into the second optical path.
Another aspect of the invention is a method of directing a light signal in an optical device, the optical device including an optical path, a trench formed in the optical path, and an alignment layer disposed on a surface of the trench, the method including disposing a switch element in the trench, the switch element including a plurality of liquid crystal molecules that are aligned in a first direction by the alignment layer when no electrical energy is applied to the switch element, and applying electrical energy to the switch element to thereby cause the plurality of molecules to align in a second direction.
Another aspect of the invention is an optical device for directing a light signal, the optical device including a substrate having an optical waveguide layer disposed thereon. The optical device also includes at least one first electrode disposed between the substrate and the optical waveguide, a trench formed in the optical waveguide, the trench having a surface area. A first alignment layer is disposed on the surface area of the trench. A liquid crystal material is disposed in the trench covering the first alignment layer. A top plate is connected to the substrate, and a second alignment layer is disposed on the top plate and adjacent to the liquid crystal material.
Another aspect of the invention is a liquid crystal cross-connect device,. including an input port for receiving light, a polarization splitter to split the received light into transverse magnetic (TM) and transverse electric (TE) components, a TM switch array connected to receive the TM components from the polarization splitter, a TE switch array connected to receive the TE components from the polarization splitter, a polarization combiner coupled to the TM switch array and the TE switch array to combine the outputs of the TM switch array and the TE switch array; and an output port coupled to the polarization combiner.
The foregoing and other aspects of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.